WIM for direct enforcement in Europe

Abstract

The use of Weigh-in-Motion for direct enforcement in Europe is reviewed. Direct enforcement by WIM was pioneered in the Czech Republic and is now operational in a number of countries, including Hungary and Belgium/Wallonia. A number of other countries are prepared to implement direct enforcement by WIM, e.g. France, Germany, Poland, and many more are in the early stages of investigating the concept. The issues required for enforcement by WIM are discussed. The various sources of weight inaccuracy are considered, potentially leading to wrongful enforcement. These include issues related to the road (slope, curve, roughness, deflection, etc.), the environment (temperature) and vehicle behaviour – lateral position on the WIM sensors and dynamic motions (bounce, roll, pitch and axle hop) induced by acceleration, braking, or other manoeuvers. Methods used to address inaccuracies are discussed, including site selection, validation of measurements, maintenance and quality assurance processes. Type approval is a particular challenge and is discussed in the context of laboratory and field tests, legislation and other local requirements. Finally, the technical and operational issues are reviewed. These include methods used by companies or drivers to avoid enforcement and how they can be addressed. The issue of lifted axles is addressed as it may change the maximum authorized mass of a vehicle or combination. Legal challenges are also discussed and how the legislation can be framed to reduce the risk of challenge.